The role of coupled DNRA-Anammox during nitrate removal in a highly saline lake.

Nitrate (NO3-) removal from aquatic ecosystems involves several microbially mediated processes, including denitrification, dissimilatory nitrate reduction to ammonium (DNRA), and anaerobic ammonium oxidation (anammox), controlled by slight changes in environmental gradients. In addition, some of these processes (i.e. denitrification) may involve the production of undesirable compounds such as nitrous oxide (N2O), an important greenhouse gas. Saline lakes are prone to the accumulation of anthropogenic contaminants, making them highly vulnerable environments to NO3- pollution. The aim of this paper was to investigate the effect of light and oxygen on the different NO3- removal pathways under highly saline conditions. For this purpose, mesocosm experiments were performed using lacustrine, undisturbed, organic-rich sediments from the Pétrola Lake (Spain), a highly saline waterbody subject to anthropogenic NO3- pollution. The revised 15N-isotope pairing technique (15N-IPT) was used to determine NO3- sink processes. Our results demonstrate for the first time the coexistence of denitrification, DNRA, and anammox processes in a highly saline lake, and how their contribution was determined by environmental conditions (oxygen and light). DNRA, and especially denitrification to N2O, were the dominant nitrogen (N) removal pathways when oxygen and/or light were present (up to 82%). In contrast, anoxia and darkness promoted NO3- reduction by DNRA (52%), combined with N loss by anammox (28%). Our results highlight the role of coupled DNRA-anammox, which has not yet been investigated in lacustrine sediments. We conclude that anoxia and darkness favored DNRA and anammox processes over denitrification and therefore to restrict N2O emissions to the atmosphere.

Spatio-temporal diversity of free-living and particle-attached prokaryotes in the tropical lagoon of Ahe atoll (Tuamotu Archipelago) and its surrounding oceanic waters.

Spatio-temporal variability of prokaryotic water column communities inside and outside a Polynesian tropical lagoon subjected to pearl oysters farming was assessed in terms of abundance by quantitative PCR and diversity by DGGE. Communities and operational taxonomic units (OTUs) were analysed according to dry/rainy seasons and free-living/particle-attached state. Bacterial density was higher in the lagoon compared to ocean and a seasonal trend was observed. No influence of the localisation within lagoon or of the planktonic/attached states was noticed on bacterial abundance and diversity. The OTUs belonged to Cyanobacteria, to heterotrophic groups in Proteobacteria and Flavobacteria. Archaeal abundance showed seasonal tendency and particle-prevalence, but no effect of lagoon or oceanic location was observed. Lagoon and oceanic archaeal diversity were different and Euryarchaeota (MG-II, MBG, and Halobacteria) were detected. During the dry season, planktonic and particle-associated community differed, whereas at rainy season, both communities were similar and included members usually associated with coral.

[Study of 206 transfused sickle cell disease patients: immunization, transfusion safety and red blood cell supply]. / Etude d'une cohorte de 206 patients drépanocytaires adultes transfusés: immunisation, risque transfusionnel et ressources en concentrés globulaires.

BACKGROUND: Prevention of hemolytic transfusion reactions depends upon our capacity to prevent allo-immunization and conflicts between antigens of transfused red blood cells and antibodies produced by the recipient. In this study, we show that to secure transfusion of sickle cell disease patients, it is necessary to take into account their immunohematologic characteristics in the organization of transfusion. METHODS AND RESULTS: Immunohematological data of 206 chronically transfused patients have been collected as well as phenotypes of transfused units. In order to prevent allo-immunization against C and E antigens for patients typed D+C-E-c+e+ (56%), 26% of the transfused units were D-C-E-c+e+. We found that 47% of the patients had a history of allo-immunization, whereas only 15% produced an antibody the day of inclusion in the study. The non-detectable antibodies were frequently known as dangerous for transfusion. Finally, this study shows the frequency of anti-D in D+ patients and anti-C in C+ patients, pointing out the question of partial antigens. CONCLUSION: To insure optimal transfusion safety for sickle cell disease patients, three points have to be improved: blood donation within the Afro-Caribbean community living in France, access to history of immuno-hematological data, detection of variant antigens, especially within the RH blood system.

[ABO incompatibility and non myeloablative allogeneic stem cell transplantation]. / Incompatibilité ABO et greffe allogénique de cellules souches hématopoïétiques à l'ère des conditionnements non myéloablatifs.

ABO incompatibility is not a barrier for allogeneic hematopoietic stem cell transplantation but is associated with specific complications. Major ABO incompatibility is associated with delayed erythroid engraftment, increased transfusion requirement and cases of pure red cell aplasia. Minor ABO incompatibility may be responsible for acute haemolytic reactions in the first months following transplantation. The widely used non myeloablative conditioning regimens might modify the management of ABO incompatibility. They could favour pure red cell aplasia development in the setting of major ABO mismatch since they are associated with a prolonged persistence of host anti-donor isohemagglutinins after allogeneic hematopoietic stem cell transplantation. In the setting of minor ABO incompatibility, the use of peripheral blood stem cells and the nature of graft-versus-host disease prophylaxis regimen may have an impact on the incidence of haemolytic reactions. In that review, the clinical and therapeutic aspects of ABO incompatibility are studied, especially regarding the impact of the conditioning regimen intensity.

Impact of nonmyeloablative conditioning regimens on the occurrence of pure red cell aplasia after ABO-incompatible allogeneic haematopoietic stem cell transplantation.

BACKGROUND AND OBJECTIVES: In the setting of major ABO-incompatible allogeneic haematopoietic stem cell transplantation (HSCT), pure red cell aplasia (PRCA) is linked to the persistence of host residual plasma cells secreting antidonor isohaemagglutinins (HA) after transplantation. There are conflicting results regarding the impact of the intensity of conditioning regimen on the occurrence of PRCA after major ABO-mismatched HSCT. MATERIAL AND METHODS: To address this question, we compared two cases occurring after nonmyeloablative (NMA) and myeloablative (MA) HSCT and reviewed previous cases reported in the NMA setting. RESULTS AND CONCLUSIONS: We observed a delayed disappearance of antidonor HAs in the NMA setting, associated to a more prolonged period of red blood cells transfusion dependence than in the MA setting. In our case as in several others, the disappearance of antidonor HAs and resolution of PRCA were observed after reinforcement of the graft-versus-host effect (i.e. immunosuppression removal or donor leukocytes infusion).

Molecular, biochemical, and physiological approaches for understanding the ecology of denitrification.

One of the major challenges in microbial ecology for the future is to establish links between structural and functional biodiversity. This is particularly difficult when one is interested in a phylogenetically diversified function such as denitrification. The data banks are very rich in functional gene sequences (nirS in this study), but most of them were obtained from not yet cultivated bacteria, and thus must be supplemented by sequences of organisms from the environment for which we could associate a taxonomic position and physiological characteristics. Combined analysis including molecular (16S-rRNA or nirS genes), physiological, and biochemical approaches was carried out on a bacterial set of 89 strains isolated from marine sediment. The denaturing gradient gel electrophoresis (DGGE) technique was successfully applied on unclamped polymerase chain reaction (PCR) products of nirS genes to compare the picture of the biodiversity obtained with 16S rRNA and nirS genes. The diversity of nirS genes and denitrifier characteristics were found within several of the 16S rDNA phylotypes. In contrast, the nirS phylotypes were no diverse both with respect to 16S rDNA and to physiology and biochemistry of denitrification. Sequences of the nirS PCR products were very close to marine environmental clones and were analyzed within the same phylogenetic tree.

Age of acquisition and word frequency in written picture naming.

This study investigates age of acquisition (AoA) and word frequency effects in both spoken and written picture naming. In the first two experiments, reliable AoA effects on object naming speed, with objective word frequency controlled for, were found in both spoken (Experiment 1) and written picture naming (Experiment 2). In contrast, no reliable objective word frequency effects were observed on naming speed, with AoA controlled for, in either spoken (Experiment 3) or written (Experiment 4) picture naming. The implications of the findings for written picture naming are briefly discussed.

Metabolic differences between attached and free-living marine bacteria: inadequacy of liquid cultures for describing in situ bacterial activity.

Marinobacter sp. strain CAB was cultivated with or without porous glass beads as solid support. Two substrates were used: the hydrophilic sodium lactate and a hydrophobic C(18)-isoprenoid ketone (6,10,14-trimethylpentadecan-2-one (TMP)). The substrate adsorption onto the beads was measured. Bacterial adhesion was determined by a direct count technique and amounted to 70% of total cells. In the immobilised cell cultures (ICC), generation times were 1.5 and 1.8 times shorter than in the planktonic cultures (FCC) with sodium lactate and with TMP, respectively. In ICC, the growth yields were lower (15.3(FCC) x 10(9) and 0.8(ICC) x 10(9) bacteria mg(-1) of sodium lactate; 50(FCC) x 10(9) and 35(ICC) x 10(9) bacteria mg(-1) of TMP). The mineralisation of substrates was estimated after mass spectrometric determination of the CO2 production rates of both free and immobilised cell cultures. The results indicated a higher specific CO2 production rate in the ICC with sodium lactate (3.1(FCC)+/-0.2 and 3.5(ICC)+/-0.3 nmol CO2 mg(-1) protein min(-1)) but not in the ICC with TMP (1.9(FCC)+/-0.7 and 0.5(ICC)+/-0.3 nmol CO2 mg(-1) protein min(-1)). The affinities for the two substrates were lower in the presence of the solid support (K(m,ICC)=18.2+/-0.2 microM and 37.1+/-2.0 microM, for sodium lactate and TMP, respectively) than without support (K(m,FCC)=8.5+/-1.5 microM and 8.4+/-1.2 microM, for sodium lactate and TMP, respectively). Moreover, the presence of a solid support showed a lower inhibition by the TMP (K(i,FCC)=3.8+/-1.0 microM and K(i,ICC)=12.2+/-2.5 microM) which may explain why the immobilised cell cultures degraded hydrophobic TMP more efficiently than the planktonic cultures.

Influence of oxygen supply on heptadecane mineralization by Pseudomonas nautica.

The influence of different states of oxygen supply on heptadecane mineralization has been investigated in resting cell suspensions of Pseudomonas nautica. The rate of heptadecane biodegraded was constant for oxygen concentrations between 21% and 10% (v/v) (about 100% and 50% of air saturation, 230 and 110 microM, respectively). A decline in biodegradation rates occurred for oxygen concentrations below 10% (about 50% of air saturation, 110 microM) and biodegradation stopped with 0.21% oxygen (2.3 microM). In the presence of 1% (11 microM) of oxygen, no CO2 was produced, showing that complete mineralisation of heptadecane was blocked.

Writing words from pictures: what representations are activated, and when?

In three experiments, the nature of the representations involved in written picture naming and the time course of their activation were investigated. French participants had to produce picture names while hearing distractors. In Experiment 1, distractors semantically related to the picture names yielded a semantic interference effect when a stimulus onset asynchrony (SOA) of--150 msec, but not when a SOA of 0 msec, was used, in both spoken and written picture naming. Experiment 2 showed that the semantic interference effect was not located at the conceptual level. In Experiment 3, participants wrote down picture names while hearing semantically related, phonologically related, both semantically and phonologically related, or unrelated distractors, presented at both SOAs. A semantic interference effect was obtained with phonologically unrelated distractors but was eliminated with phonologically related distractors. Facilitatory effects of phonologically related distractors were found at both SOAs. The implications of the findings for written picture naming are discussed.

Comparison of methods for quantification of cytochrome cd(1)-denitrifying bacteria in environmental marine samples.

Two PCR primer sets were developed for the detection and quantification of cytochrome cd(1)-denitrifying bacteria in environmental marine samples. The specificity and sensitivity of these primers were tested. Both primer sets were suitable for detection, but only one set, cd3F-cd4R, was suitable for the quantification and enumeration of the functional community using most-probable-number PCR and competitive PCR techniques. Quantification of cytochrome cd(1) denitrifiers taken from marine sediment and water samples was achieved using two different molecular techniques which target the nirS gene, and the results were compared to those obtained by using the classical cultivation method. Enumerations using both molecular techniques yielded similar results in seawater and sediment samples. However, both molecular techniques showed 1,000 or 10 times more cytochrome cd(1) denitrifiers in the sediment or water samples, respectively, than were found by use of the conventional cultivation method for counting.

Biodegradation of free phytol by bacterial communities isolated from marine sediments under aerobic and denitrifying conditions.

Biodegradation of (E)-phytol [3,7,11, 15-tetramethylhexadec-2(E)-en-1-ol] by two bacterial communities isolated from recent marine sediments under aerobic and denitrifying conditions was studied at 20 degrees C. This isoprenoid alcohol is metabolized efficiently by these two bacterial communities via 6,10, 14-trimethylpentadecan-2-one and (E)-phytenic acid. The first step in both aerobic and anaerobic bacterial degradation of (E)-phytol involves the transient production of (E)-phytenal, which in turn can be abiotically converted to 6,10,14-trimethylpentadecan-2-one. Most of the isoprenoid metabolites identified in vitro could be detected in a fresh sediment core collected at the same site as the sediments used for the incubations. Since (E)-phytenal is less sensitive to abiotic degradation at the temperature of the sediments (15 degrees C), the major part of (E)-phytol appeared to be biodegraded in situ via (E)-phytenic acid. (Z)- and (E)-phytenic acids are present in particularly large quantities in the upper section of the core, and their concentrations quickly decrease with depth in the core. This degradation (which takes place without significant production of phytanic acid) is attributed to the involvement of alternating beta-decarboxymethylation and beta-oxidation reaction sequences induced by denitrifiers. Despite the low nitrate concentration of marine sediments, denitrifying bacteria seem to play a significant role in the mineralization of (E)-phytol.

Masked form priming in writing words from pictures: evidence for direct retrieval of orthographic codes.

Three experiments used the masked priming paradigm to investigate the role of orthographic and phonological information in written picture naming. In all the experiments, participants had to write the names of pictures as quickly as possible under three different priming conditions. Nonword primes could be: (1) phonologically and orthographically related to the picture name; (2) orthographically related as in (1) but phonologically related to a lesser degree than in (1); (3) orthographically and phonologically unrelated except for the first consonant (or consonant cluster). Orthographic priming effects were observed with a prime exposure duration of 34 ms (Experiments 1 and 2) and of 51 ms (Experiment 3). In none of the experiments, did homophony between primes and picture names yield an additional advantage. Taken together, these findings support the view of the direct retrieval of orthographic information through lexical access in written picture naming, and thus argue against the traditional view that the retrieval of orthographic codes of obligatorily mediated by phonology.

Apparent reactivation of a red cell alloantibody in a healthy individual after G-CSF administration.

Granulocyte-colony stimulating factor (G-CSF) has been successfully administered to healthy subjects to mobilize peripheral blood stem cells (PBSC) for allogeneic transplantation. Adverse events are moderate. We report the first case of apparent reactivation of an alloantibody to a blood cell antigen (Jk(a)) after G-CSF administration to a healthy subject and its transmission to the PBSC transplant recipient; no concomitant reactivation of other alloantibodies was detected. This case raises questions on the effect of G-CSF on the immune system and its safety in healthy individuals.

In vitro study of a Nd:YAP laser in endodontic retreatment.

Nd:YAP laser is a dental laser with a 1340 nm wavelength. The laser beam is carried by a 200 to 300 microns fiberoptic and is suitable for endodontic therapy. We used the Nd:YAP laser in an in vitro experiment to study its effectiveness in endodontic retreatment. Temperature measurements and irradiation parameters were first defined. Then Nd:YAP laser irradiation was used, alone or in combination with hand instruments, to remove various canal sealers and broken instruments. Clinical parameters were monitored and scanning electron microscopic observations were conducted. When used at 200 mJ--with a pulse duration of 150 ms, an exposure time of 1 s and a frequency of 10 Hz--Nd:YAP laser preserved the dentinal walls of the root canal and enabled root canal retreatment without thermic elevation harming periodontal tissue. It is concluded that, in combination with hand instruments, the Nd:YAP laser is an effective device for root canal preparation in endodontic retreatment.

A peptide inhibitor of cholesteryl ester transfer protein identified by screening a bacteriophage display library.

We screened a bacteriophage display library of random decapeptides to identify peptide inhibitors of cholesteryl ester transfer protein (CETP). After affinity selection against CETP, bacteriophage-infected Escherichia coli were plated at clonal density and 36 random clones were isolated. Analysis of the relevant portion of the bacteriophage DNA from a group of 12 clones that had a relatively high affinity for CETP revealed that the corresponding amino acid sequences of the displayed peptides exhibited an ... Xaa-Arg-Met-Arg-Tyr-Xaa ... composite motif. Based on those results, decapeptides from this group were synthesized and one of them, DP1 (NH2-VTWRMWYVPA-COOH), inhibited CETP-catalyzed transfer of cholesteryl esters and triglycerides. Amino- and carboxy-terminal truncations of DP1 demonstrated that the original decapeptide could be reduced to a pentapeptide without loss of either its ability to bind to CETP or its ability to inhibit CETP-mediated lipid transfer. That pentapeptide, NH2-WRMWY-COOH (WRMWY, PNU-107368E), binds directly to CETP and its inhibition is consistent with that of a competitive inhibitor of CETP with a Ki of 164 microM. WRMWY or modified versions of this peptide may be useful in studying the interactions between CETP and plasma lipoproteins.

The demographic characteristics of Medicaid-eligible uninsured children.

OBJECTIVES: This study estimated the number of uninsured children in 1993 who were eligible for Medicaid. METHODS: Data from the March 1990 and 1994 Current Population Surveys were analyzed. RESULTS: At least 2.3 million Medicaid-eligible children were uninsured in 1993. These children were more likely to have a working parent than children on Medicaid. Higher proportions of uninsured children less than 6 years of age, children who lived in female-headed single-parent families, and African-American and Hispanic children were eligible for Medicaid. CONCLUSIONS: Many eligible children do not enroll in Medicaid, and they differ in specific ways from enrolled children.

Aerobic and anaerobic metabolism of 6,10,14-trimethylpentadecan-2-one by a denitrifying bacterium isolated from marine sediments.

This report describes the metabolism of 6,10,14-trimethylpentadecan-2-one by a denitrifying bacterium (Marinobacter sp. strain CAB) isolated from marine sediments. Under aerobic and denitrifying conditions, this strain efficiently degraded this ubiquitous isoprenoid ketone. Several bacterial metabolites, 4,8,12-trimethyl-tridecan-1-ol, 4,8,12-trimethyltridecanal, 4,8,12-trimethyltridecanoic acid, Z-3,7-dimethylocten-2-oic acid, Z-3,7,11-trimethyldodecen-2-oic acid, and 6,10,14-trimethylpentadecan-2-ol, were formally identified, and different pathways were proposed to explain the formation of such isoprenoid compounds.

In vitro evaluation of the antibacterial effects of intracanal micro plasma system treatment.

Forty freshly extracted single-rooted teeth were prepared to a size 25 master apical file, autoclaved, and inoculated with a known quantity of Actinomyces naeslundii. The teeth were divided into four groups (n = 10), including an untreated control group. The three treatment groups were exposed to Micro Plasma System (MPS), 0.5% NaOCl and 0.5% NaOCl + MPS respectively. The content of each root canal was absorbed by sterile paper points, diluted in 2 ml Schaedler Broth Medium, and incubated on blood agar. The number of CFU was determined. Data analysis, using an analysis of variance and Scheffe's test at the 1% level (Statview II software), indicated a significant reduction in CFU count for the three treatment groups compared to the control group. For the three treatment groups, no significant intergroup differences were observed.

In vitro and in vivo inhibition of rat vascular smooth muscle cell migration and proliferation by a 2-aminochromone U-86983.

Vascular smooth muscle cell migration and proliferation are the primary events that govern neointimal thickening and thus they determine the extent to which delayed restenosis occurs after percutaneous transluminal coronary angioplasty. In this study, the in vitro and in vivo smooth muscle cell antichemotactic and antiproliferative properties of a 2-aminochromone, 2-(4-morpholinyl)-8-(3-pyridinylmethoxy)-4H-1-benzopyran-4-one (U-86983), were examined. Migration and proliferation of early-passage rat vascular smooth muscle cells were inhibited by U-86983 in a concentration-dependent manner (IC50S, approximately 10 microM and 3.5 microM, respectively). Longer-term studies showed that the proliferation of smooth muscle cells was inhibited by U-86983 for at least 7 days and was fully reversible on removal of the drug. In addition, the effect of U-86983 on neointimal formation was examined in rats subjected to left common carotid artery balloon dilatation injury. Continual (2-week) i.v. administration of U-86983 (216 mg kg-1 day-1) resulted in a mean plasma drug concentration of 2.39 micrograms/ml (blood level, approximately 3.5 microM) and a 42% (P = .003) reduction in the neointima/media ratio of the injured artery. In agreement with the in vitro reversibility results, administration of U-86983 for only 2, 4 or 7 days did not affect significantly the neointimal thickness measured at 14 days, which indicated that the stimuli for smooth muscle cell migration and/or proliferation were still present 1 week after injury.(ABSTRACT TRUNCATED AT 250 WORDS)